Novel conductive agent doping/coating lithium iron phosphate material and its production method

A technology of lithium iron phosphate and conductive agent, which is applied in chemical instruments and methods, electrode manufacturing, circuits, etc., can solve the problems of lithium iron phosphate performance impact, electrochemical capacity loss, and poor high-rate discharge performance, so as to improve discharge and discharge performance. The effects of cycle stability, high-rate charge-discharge performance, high conductivity and bulk density

Inactive Publication Date: 2008-07-16
NANKAI UNIV
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  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

However, lithium iron phosphate has two obvious disadvantages: one is the low electrical conductivity, which leads to poor high-rate discharge performance and low actual specific capacity. In the case of high current, the electrode polarization is serious, resulting in increased irreversibility of charge and discharge. Large, serious loss of electrochemical capacity; second, low bulk density, resulting in low volume specific capacity, which brings certain difficulties to the practical use of lithium iron phosphate
Among them, the effect of adding a conductive agent is the most significant, and it is easy to industrialize. However, most conductive agents are different carbon materials and carbon sources. When the conductivity of lithium iron phosphate increases, its vibration will be reduced due to the addition of conductive agent carbon materials. Density, the two disadvantages cannot be overcome at the same time
In addition, the synthesis method also has a certain influence on the performance of lithium iron phosphate

Method used

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  • Novel conductive agent doping/coating lithium iron phosphate material and its production method

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Experimental program
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Effect test

Embodiment 1

[0041] Weigh Fe(NO 3 ) 3 9H 2 O 4.04g, NH 4 h 2 PO 4 1.15g, respectively dissolved in 100mL deionized water, added dropwise and mixed, under stirring, 1 mol / L ammonia water was added at 60°C until the pH of the solution was 5, filtered, washed and dried at 80°C. The resulting precursor and 0.388g Li 2 CO 3 , 0.079gCoS 2 Mix and grind, put into porcelain crucible. at a velocity of 1dm 3 min -1 99.999% argon flow, at 3°C·min -1Raise the temperature to 350°C at the same rate, keep it for 4 hours, cool down to room temperature naturally, grind and press into tablets, then raise the temperature to 500°C at the same rate, and keep it for 18 hours. Naturally cool to room temperature with the furnace, take out the product and grind to obtain the doped lithium iron phosphate.

[0042] The XRD of the product is shown in Figure 1. It can be seen from Figure 1 that olivine-type lithium iron phosphate, CoS 2 The coating did not change its crystal form, and there were no other...

Embodiment 2

[0044] Weigh Fe(NO 3 ) 3 9H 2 O 4.04g, NH 4 h 2 PO 4 1.15 g, respectively dissolved in 100 mL deionized water, added dropwise and mixed, added 1 mol / L ammonia water at 60°C under stirring until the pH value of the solution was 5, filtered, washed and dried at 80°C. The resulting precursor and 0.388g Li 2 CO 3 , mixed and ground, put into a porcelain crucible, at a flow rate of 1dm 3 min -1 99.999% argon flow, at 3°C·min -1 Raise the temperature to 350°C at the same rate, keep it for 4 hours, cool down to room temperature naturally, grind and press into tablets, then raise the temperature to 700°C at the same rate, and keep it for 18 hours. Naturally cool to room temperature with the furnace, take out the product and grind finely to obtain lithium iron phosphate. Weigh 0.0607g Co(AC) 2 4H 2 O and 0.0927g NH 2 CSNH 2 Dissolve in 20mL of ethanol, add 0.3g of the prepared lithium iron phosphate, disperse by ultrasonic wave for 0.5 hours, then place the mixture in a ...

Embodiment 3

[0046] Weigh Fe(NO 3 ) 3 9H 2 O 4.04g, NH 4 h 2 PO 4 1.15 g, respectively dissolved in 100 mL deionized water, added dropwise and mixed, added 1 mol / L ammonia water at 60°C under stirring until the pH value of the solution was 5, filtered, washed and dried at 80°C. The resulting precursor and 0.388g Li 2 CO 3 , mixed and ground, put into a porcelain crucible, at a flow rate of 1dm 3 min -1 99.999% argon flow, at 3°C·min -1 Raise the temperature to 350°C at the same rate, keep it for 4 hours, cool down to room temperature naturally, grind and press into tablets, then raise the temperature to 700°C at the same rate, and keep it for 18 hours. Naturally cool to room temperature with the furnace, take out the product and grind finely to obtain lithium iron phosphate. Weigh 0.1128g SnCl 2 and 0.0435g CTAB were dissolved in 25mL of water, 0.3g of the prepared lithium iron phosphate was added, ultrasonically dispersed for 0.5 hours, and 0.398mL of 6.5mol L was added dropwi...

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Abstract

The invention discloses a novel lithium iron phosphate material which is adulterated /covered with conductive agents and a preparation method thereof. The lithium iron phosphate material of the invention comprises lithium source compounds, iron source compounds, phosphate radical source compounds and the conductive agents of lithium iron phosphates. The technology of the invention is simple; the material is clean and pollution-free; the cost of the material is low. The invention is suitable for industrialized mass production. Specific capacity of the obtained lithium iron phosphate material is high (more than 140 mAh/g); cyclical stability is good (more than 300 times); high rate charging and discharging performance of the lithium iron phosphate material is particularly prominent (5C capacity can still reach 80 mAh/g); conductivity and stacking density are high; diffusivity of protons is improved; contact between active materials and an electrode is increased; internal resistance of the electrode and a battery is reduced; discharging and cyclical stabilities of the electrode are obviously improved. The invention is widely applied to novel high performance lithium ion batteries.

Description

technical field [0001] The invention belongs to the technical field of energy materials, and in particular relates to a novel conductive agent-doped / coated lithium iron phosphate material and a preparation method. Background technique [0002] Since Goodenough discovered in 1997 that lithium iron phosphate with an olivine structure can reversibly intercalate and extract lithium ions, lithium iron phosphate is considered to be one of the most promising electrode materials for lithium-ion batteries. This material has many advantages: no precious metals, cheap raw materials, extremely rich resources; non-toxic, environmentally friendly; moderate working voltage (3.4V); good platform characteristics, with a flat charge and discharge voltage curve under low current , is an ideal cathode material for lithium-ion batteries; the theoretical capacity is large (170mAh g -1 ), stable structure, and excellent safety performance (O and P are firmly combined with strong covalent bonds, m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/04C01B25/45H01M4/62
CPCY02E60/10
Inventor 焦丽芳袁华堂王一菁杨琳
Owner NANKAI UNIV
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